1. Technical Field
The present invention relates to an image forming apparatus provided with a translation cam configured to cause a developing roller to come into contact with and to be retracted from a photosensitive drum.
2. Related Art
An image forming apparatus including a plurality of photosensitive drums, a plurality of developing rollers provided corresponding to the respective photosensitive drums, a translation cam configured to be movable in a linear direction so as to cause the respective developing rollers to come into contact with and to be retracted from the respective photosensitive drums, and a stepping motor configured to drive the translation cam is known. In this technology, since the translation cam can be stopped at a desired position by the stepping motor, the translation cam can be located reliably at respective positions for a color mode (a mode in which all the developing rollers are brought into contact with the photosensitive drums) or a monochrome mode (a mode in which only a developing roller for monochrome is brought into contact with the photosensitive drums), whereby operations in the respective modes can be performed satisfactorily.
In the technology described above, since the stepping motor specific for driving the translation cam is provided, there is a problem of cost increase. In contrast, driving of the translation cam using a different motor in the image forming apparatus (for example, a motor configured to drive the photosensitive drum) is contemplated.
However, in this case, if the motor is a motor having a weak holding power such as a DC motor, when the motor being driven is stopped, the motor rotates by its inertia. Consequently, the translation cam may pass over the desired position.